Abstract

Metalloproteins are redox molecules naturally shuttling electrons with high efficiency between molecular partners. As such, they are candidates of choice for bioelectronics. In this work, we have used bacterial metalloprotein azurin, hosted in a nanometer gap between two electrically biased goldelectrodes, to demonstrate an electrochemically gated single-molecule transistor operating in an aqueous environment. Gold-chemisorbed azurin shows peaks in tunneling current upon changing electrode potential and a related variation in tunneling barrier transparency which can be exploited to switch an electron current through it. These results suggest the wet approach to molecular electronics as a viable method for exploiting electron transfer of highly specialized biomolecules.

Received 29 November 2004Accepted 15 February 2005Published online 23 March 2005

Acknowledgments:

The authors thank Elisa Molinari, Stefano Corni, and Eric Chang for insightful discussions, Mauro Zapparoli for technical assistance in TEM measurements, and G.W. Canters for providing us with Zn-azurin. This work was supported in part by Istituto Nazionale per la Fisica della Materia, through Advanced Research Project Grant SINPROT, by EU FP5 IST-FET SAMBA, and by Italian Ministero dell’Istruzione, Università e Ricerca through Grant FIRB NOMADE.